Haha, my bird mount plans were mostly for epicry's sake. I feel like they would be more pack animals and travel means than speeding across terrain. They'd be faster than Turner at their sprint, but probably more like war horses. Big, flightless, strong and meaty rather than the typical flying bird. It'd be awesome to see Turner rollin' into combat with a spear on one of them.
Wish I was good enough with 3D math and the Pheonix Engine scripting to do this mod. I really should do this one. But it's just another thing for me to forget to keep updated. Haha, too many ideas; not enough time.

I hope it's not too late but I had an idea regarding the goats:
I think they should be the peaceful NPCs (kinda like the rabbit civilians) while the fighters would be rams. I, personally, don't find goats very intimidating but the drawing of the goat fighters looked pretty epic so I thought, those should be rams not goats. Rams are wilder than goats. When people look at goats they think "domesticated".
Also I'm pretty sure the "pack hierarchy" is more prominent amongst rams. They're always having head butting fights to assert dominance. I dunno I just feel that between goats and rams, rams are the more violent ones while goats are more peaceful.
They also sort of look alike. The only difference is the horns.
(That's another point: ram horns are so much more badass than goat horns. Oooooh and ibexes. Ibex horns are so badass)

to be clear, rams are basically just male sheep. I'm assuming you were meaning bighorn sheep though, because they're the most badass sheep ever. Ibex are technically a type of goat also, while mountain goats are more closely related to antelopes than goats. All of them would be awesome to see.

I like the idea of new animals, but I don't think it would work verry well. For one it's only the mammals that are humanoid so that limits it to just one group to choose from and on top of that they'd have to make unique cultures and fighting styles for each and every new race added.

That said I'd like to see alot of diversity within each species, for example; Rabbits could be separated into groups based on ear orientation(tall, floppy, short etc) and dogs could be grouped based on breed as hinted at in the web comic. But I think they are already planning this sort of thing so I pretty much just re-stated the obvious.

It'd be cool if there was stuff like squid and sharks. Sharks could be specialized in a new weapon type. So like theres Dog weapons and cat weapons. so... SHARK WEAPONS! they have like fish bone handles or Fish skeleton blades. and they can run faster and swim faster. but I don't recommend DEEP sea creatures like Angler Fish. It would be scary... But sharks would be cool . and Sea bosses would be cool. I still recommend Whaleman boss! And whaleman minions!!! the Whaleman boss. should be on a beach raining while you have to jump around on him and scenery like rocks and even icebergs. if he flicks you off his head you fly back to the beach or in the air or into the water.. either way, you die. in water you could drown or get killed by sharks. I prefer drown. and his minions will carry spears with fish on it.